MARTINEZ — In September 2015, 29-year-old Jose Claudio Munoz called 9-1-1 to report that his wife, Yvonne Hernandez, had been shot. Moments earlier, dispatchers had received a garbled emergency call from the victim, which ended with a man’s voice screaming “(expletive) you” and the line going dead.

The dispatcher asked Munoz if the shooter was still in the home, and his voice started to crack.

“I’m’a be honest, I’m’a do a confession,” Munoz responded. “I shot my wife. I have my son here with me.”

A child’s voice could be heard crying in the background. It was the couple’s 4-year-old boy.

“You killed Mommy,” he told Munoz.

What Munoz said next has become a key point in his murder trial. Jurors began deliberating Friday, after attorneys argued whether Munoz’s actions amounted to premeditated murder, or whether he acted in “the heat of passion” and was guilty of a lesser offense, as the defense argued.

“I know she’s been cheating on me,” Munoz told the dispatcher as he stood over his wife’s body. “I know she’s been trying to have me killed.”

On Friday morning, prosecutor Rachel Piersig told jurors there was “absolutely no evidence” to support either of Munoz’s claims. In fact, she said, it was the other way around: Munoz had cheated on Hernandez and she was “kicking him out” of their home. The two met in high school and had been together for 10 years, the attorneys said.

“This was not a sudden argument. … In fact, this had been building,” Piersig said, later adding, “Prior to this day, (Munoz) had thought about killing Ms. Hernandez.”

Munoz’s attorney, deputy public defender Adam Burke, told jurors the case was “an absolute tragedy” and Munoz had “lost his cool” and “acted under great emotion.” He said Munoz had been “provoked” by Hernandez’s alleged infidelity.

“When you know your wife has been cheating on you, of course you’re going to act rashly and with intense emotion,” he said.

But Burke acknowledged his client was obviously not blameless. He asked jurors to find Munoz not guilty of murder, but invited them to convict him of manslaughter with use of a firearm.

“It’s not about giving Mr. Munoz a pass or excusing his conduct,” Burke said. “Voluntary manslaughter is a violent felony…couples fight. It shouldn’t end like this.”

As evidence of Munoz’s premeditation, Piersig pointed to a bizarre discovery made during the course of the investigation: All the garments in Hernandez’s underwear drawer had been shredded, apparently by Munoz, with a knife. She called that a “very personal attack” that showed Munoz had been stirring throughout the day.

She also said the defendant had been controlling and violent with Hernandez in the past. She rebutted Burke’s contention that the violence was “a two-way street,” saying the only person who claimed Hernandez had been violent with Munoz was Munoz himself.

Hernandez was shot twice from different downward angles, once in the abdomen and once directly in the heart. A forensic pathologist testified during the two-day trial that the shot to the heart would have ended her life within 30 seconds, but he didn’t know which shot was first.

That, Piersig said, means there are two possible scenarios: that Hernandez made the phone call in the 30 seconds before she died, and that the last thing she heard was Munoz saying “(expletive) you” to her. Or, that she made the phone call after being shot in the abdomen, and that when he discovered her on the phone, he shot her again in the heart.

Their 4-year-old son witnessed the event, Piersig said, and could have easily been hurt or killed. She asked jurors to find Munoz guilty of felony child abuse.

Burke said it would be “absurd” for him to argue that the child didn’t suffer, but insisted the crime was misdemeanor child abuse, not felonious.

Before the jury was brought in Friday, one juror was replaced by an alternate after two other jurors told the judge they had seen him nod off the day before.

The juror admitted to falling asleep for “maybe a second” but said he was doing his best to pay attention. Judge John Kennedy said he thought it best to replace the juror “in an abundance of caution.” To pick the juror, he dropped the replacement names into a wooden wheel and spun it with a crank.

Nate Gartrell covers crime, politics, and corruption in Contra Costa County. He joined the Bay Area News Group in 2014. Outside of journalism, he doesn't do much. He aspires to visit all 30 Major League Baseball stadiums. Reach him at 925-779-7174.